1. Field of the Invention
The present invention relates to an image processing method and an image processing apparatus for carrying out image processing on an image including a figure, and also to a computer-readable recording medium storing a program to cause a computer to execute the image processing method.
2. Description of the Related Art
When a portrait is viewed, most attention is paid to the face of the person therein. In order to generate a high-quality photograph, the color and/or density of the face of a figure in the photograph needs to be corrected. Therefore, a method of generating a portrait having appropriate color and/or density of the face of a figure therein has been proposed (see Japanese Unexamined Patent Publication No. 6(1994)-67320, for example). In this method, a candidate area for a face is extracted by dividing a portrait based on distributions of hue and chroma values of the portrait and a face area is extracted based on a shape of an area positioned close to the candidate area. By determining exposure of a photosensitive material based on color and/or density of the face area, color and density of the face of the person become appropriate. Another method of generating a photograph including a figure whose face has appropriate color and/or density has also been proposed (see Japanese Unexamined Patent Publication No. 8(1996)-110603). In this method, a face area of a figure is extracted from a photograph generated in uneven lighting due to shade or a flash, and exposure is determined by removing the illumination variance from the face area. In this manner, each face has appropriate color and/or density in the photograph.
However, in recognition of color and density of a target area, it has been known that human vision is affected by color and density of areas surrounding the target area (Color Appearance Model, M. D. Fairchild, ADDISON-WESLEY, 1998). In other words, when surroundings are dark, an object therein looks light, while the object looks dark when the surroundings are light, even if the density of the object is actually the same in both cases. For example, when two areas having the same gray density are viewed in equal-density backgrounds, the two areas are perceived to have the same density. However, when the same areas are viewed on black and white backgrounds respectively, the density is perceived to be different between the two areas.
Therefore, even if the processing for appropriately correcting color and density of the face area is carried out as described in Japanese Unexamined Patent Publication Nos. 6(1994)-67320 and 8(1996)-110603, the color and the density of the face area may not become appropriate due to the effect caused by color and density of areas surrounding the face area.